package queue;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

/**
 * @author 程旭东
 */
public class MapTest {
    public static void main(String[] args) {
        int index = 0;
        int result = 0;
        for(int i=1;i<=101;i+=2){
            if(index%2==0){
                result = result+i;
                index++;
            }else{
                result = result-i;
                index++;
            }
        }
        System.out.println(result);
    }
}
